PUBLIC MARKS from camel with tags linux & apache

Many times, you want to execute a command not only on one server, but also on several servers. For example, find out * Version of kernel * Version of Apache web server * Update static html or images files on all web servers via rsync * Find out user information, server information, memory usage etc * Security/patch checking tentakel I have already covered how to execute commands on multiple Linux or UNIX servers via shell script. The disadvantage of script is commands do not run in parallel on all servers. However, several tools exist to automate this procedure in parallel. With the help of tool called tentakel, you run distributed command execution. It is a program for executing the same command on many hosts in parallel using ssh (it supports other methods too). Main advantage is you can create several sets of servers according requirements. For example webserver group, mail server group, home servers group etc. The command is executed in parallel on all servers in this group (time saving). By default, every result is printed to stdout (screen). The output format can be defined for each group.

mod_slotlimit is an Apache module that using dynamic slot allocation algorithm and static rules, can manage resources used for each running site.

This article explains how you can install and configure apache2-mpm-peruser on a Debian Etch server. apache2-mpm-peruser is an MPM (Multi-Processing Module) for the Apache 2 web server, very similar to apache2-mpm-itk, but faster (almost as fast as apache2-mpm-prefork). mpm-peruser allows you to run each of your vhosts under a separate UID and GID - in short, the scripts and configuration files for one vhost no longer have to be readable for all the other vhosts. It is based on metuxmpm, a working implementation of the perchild MPM. The result is a sane and secure web server environment for your users, without kludges like PHP's safe_mode.

This article shows how to install and configure ModSecurity (version 2) for use with Apache2 on a Debian Etch system. ModSecurity is an Apache module that provides intrusion detection and prevention for web applications. It aims at shielding web applications from known and unknown attacks, such as SQL injection attacks, cross-site scripting, path traversal attacks, etc. I want to say first that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!

mod_defensible is an Apache 2.x module intended to block spammers/hackers/script kiddies using DNSBL servers. It will look at the client IP and check it in one or several DNSBL servers and return a 403 Forbidden page to the client. This guide shows how to install and use it with Apache 2 on a Debian Etch server.

wtop is really cool application for web server log analysis and to see server stats at a glance. It also has powerful log grepping capability. It is just like 'top' for your webserver. It can find out number of searches or signups per seconds. It can also create histogram of response time. There is also another tool called logrep a powerful command-line program for ad-hoc analysis and filtering for log files. You can dig up lots of information using wtop tools.

This tutorial shows how to set up a two-node Apache web server cluster that provides high-availability. In front of the Apache cluster we create a load balancer that splits up incoming requests between the two Apache nodes. Because we do not want the load balancer to become another "Single Point Of Failure", we must provide high-availability for the load balancer, too. Therefore our load balancer will in fact consist out of two load balancer nodes that monitor each other using heartbeat, and if one load balancer fails, the other takes over silently.

Vlogger is a little piece of code borned to handle dealing with large amounts of virtualhost logs. It’s bad news that apache can’t do this on its own. Vlogger takes piped input from apache, splits it off to separate files based on the first field. It uses a file handle cache so it can’t run out of file descriptors. It will also start a new logfile every night at midnight, and maintain a symlink to the most recent file. For security, it can drop privileges and do a chroot to the logs directory. we need to put just one accesslog.filename directive into our global lighttpd configuration, and it will write access logs for each virtual host and day. Therefore, you do not have to split lighttpd’s overall access log into access logs for each virtual host each day, and you do not have to configure lighttpd to write one access log per virtual host

In this tutorial I will describe how to install and configure mod_cband on an Apache2 web server. mod_cband is an Apache 2 module which provides bandwidth quota and throttling. It solves the problem of limiting users' and virtualhosts' bandwidth usage. The current version can set virtualhosts' and users' bandwidth quotas, maximal download speed, requests-per-second speed and the maximal number of simultanous IP connections.

Here is my compilation of tips on how to optimise Apache on Linux for PHP and CGI programs.

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy and heartbeat on Debian Etch. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using heartbeat, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. HAProxy is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.). From the HAProxy web site: "HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for web sites crawling under very high loads while needing persistence or Layer7 processing. Supporting tens of thousands of connections is clearly realistic with todays hardware. Its mode of operation makes its integration into existing architectures very easy and riskless, while still offering the possibility not to expose fragile web servers to the Net."

Lighttpd, sometimes pronounced "Lighty", is a lightweight HTTP server that can help alleviate Apache's load by serving static content. Since Lighttpd uses less resources per request than Apache, it generally serves most static content faster than Apache. This tutorial shows how to install Lighttpd behind Apache via Apache´s proxy module.

À travers un exemple concret, nous vous proposons de déjouer les pièges de la mise en œuvre d’un cluster haute-disponibilité économique, avec équilibrage de charge et constitué uniquement de deux machines !

Pound is a reverse-proxy load balancing server. It accepts requests from HTTP / HTTPS clients and distributes them to one or more Web servers. The HTTPS requests are decrypted and passed to the back-ends as plain HTTP. It will act as: a) Server load balancer b) Reverse proxy server c) Apache reverse proxy etc d) It can detects when a backend server fails or recovers, and bases its load balancing decisions on this information: if a backend server fails, it will not receive requests until it recovers e) It can decrypts https requests to http ones f) Rejects incorrect requests h) It can be used in a chroot environment (security feature)

This article explains how to set up a two-node load balancer in an active/passive configuration with Pound and keepalived on Debian Etch. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using keepalived, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. Pound is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.).

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy and keepalived on Debian Etch. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using keepalived, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. HAProxy is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.).

This guide is about mod_macro, which makes the job of managing an Apache webserver much easier, or just for the home developer with several test pages or projects. I will explain how to get it running and give some examples of how I use the module, to help you get started with using it.

Apache server performance can be improved by adding additional hardware resources such as RAM, faster CPU, etc. But most of the time, the same result can be achieved by custom configuration of the server. This article looks into getting maximum performance out of Apache with the existing hardware resources, specifically on Linux systems. Of course, it is assumed that there is enough hardware resources - especially enough RAM that the server isn’t swapping frequently. First two sections look into various Compile-Time and Run-Time configuration options. The Run-Time section assumes that Apache is compiled with prefork MPM. HTTP compression and caching is discussed next. Finally, using separate servers for serving static and dynamic contents is covered. Basic knowledge of compiling and configuring Apache and Linux are assumed.

Applications using the LAMP (Linux®, Apache, MySQL, PHP/Perl) architecture are constantly being developed and deployed. But often the server administrator has little control over the application itself because it's written by someone else. This series of three articles discusses many of the server configuration items that can make or break an application's performance. This second article focuses on steps you can take to optimize Apache and PHP. Linux, Apache, MySQL, and PHP (or Perl) form the basis of the LAMP architecture for Web applications. Many open source packages based on LAMP components are available to solve a variety of problems. As the load on an application increases, the bottlenecks in the underlying infrastructure become more apparent in the form of slow response to user requests. The previous article showed you how to tune the Linux system and covered the basics of LAMP and performance measurement. This article focuses on the Web server components, Apache and PHP.

In this article I describe how to install and setup the Cacti in a ISPConfig Server. There aren't many differences from installing in other ISP Managers or standalone Apache installations. I tried many others solutions, but Cacti is very simple and fast to implement.

Today it is possible to create a secure website with relative ease by requiring a client to present a digitally signed certificate. A digitally signed certificate is simply a piece of information that contains data about the subject, public key, dates of validity, identification of the Certificate Authority (CA), and the digital signature. There are typically two ways to go about creating a secure website. First is by the use of a self-signed certificate. The second way is by using a Trusted Certificate signed by a CA. The choice is up to you, and this tutorial will show you how to do both. Go ahead and su into root and let's begin!

This tutorial shows how to set up a Debian Etch (Debian 4.0) based server that offers all services needed by ISPs and hosters: Apache web server (SSL-capable), Postfix mail server with SMTP-AUTH and TLS, BIND DNS server, Proftpd FTP server, MySQL server, Courier POP3/IMAP, Quota, Firewall, etc. This tutorial is written for the 32-bit version of Debian Etch, but should apply to the 64-bit version with very little modifications as well.

Secure PHP installation - Lorenzo Alberton